how to view object underground

Hello Hannah,
Is the current 1.40 version support ground view now?
I found an issue here is when I changed the position of model from above ground to underground (negative height), the camera has limitations on tilting, pitching and rotating, How can I setting the camera to get the same for underground model the effect when the model above ground? like which part should be modified in the source code?
looking forward to hearing from you.
Regards,
Ping Yang (Peter)